Autonomous driving system

ABSTRACT

An autonomous driving system controls autonomous driving of a vehicle and calculates an interest level of a driver of the vehicle for the autonomous driving. In a driver-oriented mode, the autonomous driving system gives priority to at least one of setting by the driver, will of the driver, and ride quality. In a performance-oriented mode, the autonomous driving system gives priority to at least one of increase in a safety margin, reduction in a time to arrive at a destination, improvement in fuel economy, improvement in motion performance, and reduction in a frequency of notification to the driver. The autonomous driving system controls the autonomous driving in the driver-oriented mode in a case of a normal state, and controls the autonomous driving in the performance-oriented mode in a case of a low interest state where the interest level is lower than the normal state.

BACKGROUND Technical Field

The present disclosure relates to an autonomous driving system thatcontrols autonomous driving of a vehicle.

Background Art

Patent Literature 1 discloses a vehicle control device that is capableof switching between autonomous driving and manual driving of a vehicle.When switching from the autonomous driving to the manual driving, thevehicle control device notifies a driver that the autonomous drivingwill end. Here, the vehicle control device calculates a degree of manualdriving adaptation of the driver based on a driver state, and makes thenotification timing earlier as the degree of manual driving adaptationis lower.

LIST OF RELATED ART

Patent Literature 1: Japanese Unexamined Patent Application PublicationNo. JP-2016-38768

SUMMARY

In general, autonomous driving control of a vehicle is performed withfully considering driver's preference and ride quality. When such theautonomous driving control is performed, potential performance of thevehicle is not necessarily fully exercised.

An object of the present disclosure is to provide an autonomous drivingcontrol technique that can achieve a balance between consideration for adriver and exercise of potential performance of a vehicle.

A first disclosure is directed to an autonomous driving system mountedon a vehicle.

The autonomous driving system includes:

an autonomous driving control device configured to control autonomousdriving of the vehicle; and

an interest level calculation device configured to calculate an interestlevel of a driver of the vehicle for the autonomous driving.

A low interest state is a state where the interest level is lower than anormal state.

Modes of the autonomous driving include:

a driver-oriented mode in which the autonomous driving control devicegives priority to at least one of setting by the driver, will of thedriver, and ride quality; and

a performance-oriented mode in which the autonomous driving controldevice gives priority to at least one of increase in a safety margin,reduction in a time to arrive at a destination, improvement in fueleconomy, improvement in motion performance, and reduction in a frequencyof notification to the driver.

The autonomous driving control device controls the autonomous driving inthe driver-oriented mode in a case of the normal state, and controls theautonomous driving in the performance-oriented mode in a case of the lowinterest state.

A second disclosure further has the following feature in addition to thefirst disclosure.

When increasing the safety margin in the performance-oriented mode, theautonomous driving control device performs keep left driving regardlessof the setting by the driver or the will of the driver.

A third disclosure further has the following feature in addition to thefirst disclosure.

A merge lane merges with a merged section of a first lane ahead of thevehicle.

When increasing the safety margin in the performance-oriented mode, theautonomous driving control device makes the vehicle travel so as toavoid the merged section regardless of the setting by the driver or thewill of the driver.

A fourth disclosure further has the following feature in addition to thefirst disclosure.

The autonomous driving control device performs the autonomous drivingwith a margin distance to a surrounding vehicle.

When increasing the safety margin in the performance-oriented mode, theautonomous driving control device increases the margin distance ascompared with a case of the driver-oriented mode.

A fifth disclosure further has the following feature in addition to thefirst disclosure.

When a lane changeable condition is satisfied, the autonomous drivingcontrol device judges that a lane change is possible.

When increasing the safety margin in the performance-oriented mode, theautonomous driving control device makes the lane changeable condition beharder to satisfy as compared with a case of the driver-oriented mode.

A sixth disclosure further has the following feature in addition to thefirst disclosure.

When an overtaking execution condition is satisfied, the autonomousdriving control device starts overtaking processing for overtaking apreceding vehicle.

The overtaking execution condition includes that an inter-vehicledistance between the vehicle and the preceding vehicle is less than afirst threshold.

When increasing the safety margin in the performance-oriented mode, theautonomous driving control device increases the first threshold ascompared with a case of the driver-oriented mode.

A seventh disclosure further has the following feature in addition tothe first disclosure.

When an overtaking execution condition is satisfied, the autonomousdriving control device starts overtaking processing for overtaking apreceding vehicle.

The overtaking execution condition includes that a relative speedbetween the vehicle and the preceding vehicle is equal to or more than asecond threshold.

When reducing the time to arrive at the destination in theperformance-oriented mode, the autonomous driving control devicedecreases the second threshold as compared with a case of thedriver-oriented mode.

An eighth disclosure further has the following feature in addition tothe first disclosure.

When improving the motion performance in the performance-oriented mode,the autonomous driving control device increases upper limits ofacceleration and deceleration of the vehicle as compared with a case ofthe driver-oriented mode.

A ninth disclosure further has the following feature in addition to thefirst disclosure.

When improving the motion performance in the performance-oriented mode,the autonomous driving control device advances a start timing of a lanechange as compared with a case of the driver-oriented mode.

A tenth disclosure further has the following feature in addition to thefirst disclosure.

When reducing the frequency of notification in the performance-orientedmode, the autonomous driving control device performs the autonomousdriving without asking the will of the driver.

The autonomous driving system according to the present disclosurecontrols the autonomous driving in the driver-oriented mode in the caseof the normal state, and controls the autonomous driving in theperformance-oriented mode in the case of the low interest state. It isthus possible to exercise the potential performance of the vehiclewithout giving the driver a feeling of strangeness. In other words, itis possible to achieve a balance between consideration for the driverand exercise of the potential performance of the vehicle.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram for explaining an autonomous drivingsystem according to an embodiment of the present disclosure;

FIG. 2 is a block diagram schematically showing a configuration of theautonomous driving system according to the embodiment of the presentdisclosure;

FIG. 3 is a block diagram showing a concrete configuration example ofthe autonomous driving system according to the embodiment of the presentdisclosure;

FIG. 4 is a block diagram showing an example of driving environmentinformation used in the autonomous driving system according to theembodiment of the present disclosure;

FIG. 5 is a flow chart showing processing by a control device of theautonomous driving system according to the embodiment of the presentdisclosure;

FIG. 6 is conceptual diagram showing concrete examples of autonomousdriving control in a performance-oriented mode by the autonomous drivingsystem according to the embodiment of the present disclosure;

FIG. 7 is a flow chart showing an example of lane planning by theautonomous driving system according to the embodiment of the presentdisclosure;

FIG. 8 is a conceptual diagram for explaining an example of laneplanning by the autonomous driving system according to the embodiment ofthe present disclosure;

FIG. 9 is a conceptual diagram for explaining another example of laneplanning by the autonomous driving system according to the embodiment ofthe present disclosure;

FIG. 10 is a conceptual diagram for explaining a still another exampleof lane planning by the autonomous driving system according to theembodiment of the present disclosure;

FIG. 11 is a conceptual diagram for explaining a still another exampleof lane planning by the autonomous driving system according to theembodiment of the present disclosure;

FIG. 12 is a conceptual diagram for explaining a margin distance to asurrounding vehicle in the embodiment of the present disclosure;

FIG. 13 is a conceptual diagram for explaining a lane changeablecondition in the embodiment of the present disclosure;

FIG. 14 is a conceptual diagram for explaining an overtaking executioncondition in the embodiment of the present disclosure; and

FIG. 15 is a conceptual diagram for explaining a still another exampleof lane planning by the autonomous driving system according to theembodiment of the present disclosure.

EMBODIMENTS

Embodiments of the present disclosure will be described below withreference to the attached drawings.

1. Outline

FIG. 1 is a conceptual diagram for explaining an autonomous drivingsystem 10 according to the present embodiment. The autonomous drivingsystem 10 is mounted on a vehicle 1 and controls autonomous driving ofthe vehicle 1. For example, the autonomous driving system 10 controlstravel of the vehicle 1 during the autonomous driving. The autonomousdriving system 10 is provided with at least two autonomous drivingmodes.

A first autonomous driving mode is a “driver-oriented mode”. In thedriver-oriented mode, the autonomous driving system 10 performs theautonomous driving control with giving priority to consideration for adriver of the vehicle 1. More specifically, the autonomous drivingsystem 10 performs the autonomous driving control with giving priorityto at least one of setting by the driver, will (selection, instruction)of the driver, and ride quality. An example of the setting by the driveris an inter-vehicle distance to a preceding vehicle that is set to adesired value by the driver. An example of the will of the driver isapproval/refusal of a lane change proposed by the autonomous drivingsystem 10.

A second autonomous driving mode is a “performance-oriented mode”. Inthe performance-oriented mode, the autonomous driving system 10 performsthe autonomous driving control with giving priority to exercise ofpotential performance of the vehicle 1. More specifically, theautonomous driving system 10 performs the autonomous driving controlwith giving priority to at least one of the following standpoints (A) to(E).

(A) Increase in safety margin

(B) Reduction in time to arrive at destination

(C) Improvement in fuel economy

(D) Improvement in motion performance

(E) Reduction in frequency of notification to driver

The autonomous driving system 10 according to the present embodimentswitches the autonomous driving mode according to a state of the driver.More specifically, the autonomous driving system 10 switches between thedriver-oriented mode and the performance-oriented mode according to an“interest level IL” of the driver. The interest level IL is a degree ofthe driver's interest in the autonomous driving of the vehicle 1.

A state where the interest level IL is comparatively high is hereinafterreferred to as a “normal state”. In a case of the normal state, theautonomous driving system 10 gives priority to consideration for thedriver and performs the autonomous driving control in thedriver-oriented mode. On the other hand, for example, when the driverviews contents in the vehicle 1, the interest level IL for theautonomous driving is low. In such a state where the interest level ILis low, the driver scarcely has a feeling of strangeness about theautonomous driving control even when consideration for the driver is notgiven priority. Therefore, in a case of a “low interest state” where theinterest level IL is comparatively low, the autonomous driving system 10performs the autonomous driving control in the performance-oriented modein order to exercise the potential performance of the vehicle 1.

As described above, the autonomous driving system 10 according to thepresent embodiment controls the autonomous driving in thedriver-oriented mode in the case of the normal state, and controls theautonomous driving in the performance-oriented mode in the case of thelow interest state. It is thus possible to exercise the potentialperformance of the vehicle 1 without giving the driver a feeling ofstrangeness. In other words, it is possible to achieve a balance betweenconsideration for the driver and exercise of the potential performanceof the vehicle 1.

2. Autonomous Driving System

2-1. Overall Configuration Example

FIG. 2 is a block diagram schematically showing a configuration of theautonomous driving system 10 according to the present embodiment. Theautonomous driving system 10 includes an information acquisition device20, an autonomous driving control device 30, and an interest levelcalculation device 40.

The information acquisition device 20 acquires driving environmentinformation 50 indicating driving environment for the vehicle 1. Theautonomous driving control device 30 controls the autonomous driving ofthe vehicle 1 based on the driving environment information 50. Theinterest level calculation device 40 calculates the interest level IL ofthe driver for the autonomous driving. The autonomous driving controldevice 30 controls the autonomous driving of the vehicle 1 according tothe interest level IL.

FIG. 3 is a block diagram showing a concrete configuration example ofthe autonomous driving system 10. The autonomous driving system 10 isprovided with a control device 100, a GPS (Global Positioning System)receiver 110, a map database 120, a sensor group 130, a communicationdevice 140, an HMI (Human Machine Interface) unit 150, a driver monitor160, and a travel device 180.

The control device 100 controls the autonomous driving of the vehicle 1.The control device 100 is a microcomputer including a processor and amemory device. The control device 100 is also called an ECU (ElectronicControl Unit). The autonomous driving control by the control device 100is achieved by the processor executing a control program stored in thememory device.

The GPS receiver 110 receives signals transmitted from a plurality ofGPS satellites and calculates a position and an orientation of thevehicle 1 based on the received signals.

Map information is recorded in the map database 120. The map informationincludes information of lane geometries, lane attributes (e.g. slowertraffic lane, speed limit), autonomous driving permitted zones, and thelike.

The sensor group 130 detects a situation around the vehicle 1 and astate of the vehicle 1. The sensor group 130 is exemplified by a LIDAR(Laser Imaging Detection and Ranging), a radar, and a camera. Inaddition, the sensor group 130 includes a vehicle state sensor thatdetects a state of the vehicle 1. The vehicle state sensor includes avehicle speed sensor that detects a speed of the vehicle 1.

The communication device 140 communicates with the outside of thevehicle 1. For example, the communication device 140 performs a V2Icommunication (a vehicle-to-infrastructure communication) and a V2Vcommunication (a vehicle-to-vehicle communication). In addition, thecommunication device 140 may communicate with a management servermanaging autonomous driving service through a communication network.

The HMI unit 150 is an interface for proving the driver with informationand receiving information from the driver. More specifically, the HMIunit 150 includes an input device and an output device. The input deviceis exemplified by a touch panel, a switch, a microphone, and the like.The output device is exemplified by a display device, a speaker, and thelike. The output device is used for a variety of notifications (e.g.lane change proposal) from the autonomous driving system 10 to thedriver. The input device is used by the driver for communicatingpreferred settings (e.g. inter-vehicle distance, vehicle speed) and thedriver's will (e.g. approval or refusal of lane change proposal) to theautonomous driving system 10.

The driver monitor 160 detects a state of the driver through imaging.More specifically, the driver monitor 160 includes an imaging devicesuch as an infrared camera. The driver monitor 160 is capable ofdetecting various kinds of the state of the driver by analyzing an imageobtained by the imaging device. For example, the driver monitor 160 candetect an orientation of a face, a direction of eyes, and an eyeopening/closing degree of the driver.

The media device 170 is a device for the driver to view contents. Themedia device 170 includes a monitor that displays videos and images, anda speaker that outputs sounds. The media device 170 may be included inthe HMI unit 150.

The travel device 180 includes a steering device, a driving device, abraking device, and a turn signal. The steering device turns wheels. Thedriving device is a power source that generates a driving force. Thedriving device is exemplified by an engine and an electric motor. Thebraking device generates a braking force.

2-2. Information Acquisition Device

The control device 100 acquires the driving environment information 50by using the GPS receiver 110, the map database 120, the sensor group130, the communication device 140, the HMI unit 150, and the drivermonitor 160.

FIG. 4 shows an example of the driving environment information 50 in thepresent embodiment. The driving environment information 50 includesposition-orientation information 51, map information 52, sensor-detectedinformation 53, delivery information 54, driver input information 55,and driver monitor information 56.

The position-orientation information 51 indicates the position and theorientation of the vehicle 1. The control device 100 acquires theposition-orientation information 51 from the GPS receiver 110.

The map information 52 includes information of lane geometries, laneattributes (e.g. slower traffic lane, speed limit), autonomous drivingpermitted zones, and the like. The control device 100 acquires the mapinformation 52 around the vehicle 1 based on the position-orientationinformation 51 and the map database 120.

The sensor-detected information 53 is information acquired based on aresult of detection by the sensor group 130. More specifically, thesensor-detected information 53 includes target information regarding atarget around the vehicle 1. The target around the vehicle 1 isexemplified by a surrounding vehicle, a fallen object, a white line, aroadside structure, a sign, and so forth. The target informationincludes a relative position, a relative speed, and the like of thedetected target as seen from the vehicle 1. In addition, thesensor-detected information 53 includes the state of the vehicle 1detected by the vehicle state sensor. The control device 100 acquiresthe sensor-detected information 53 based on the result of detection bythe sensor group 130.

The delivery information 54 is information acquired through thecommunication device 140. For example, the delivery information 54includes road traffic information (traffic jam information, road workzone information, accident information, traffic regulation information,and the like) delivered from an infrastructure. The delivery information54 may include information delivered from the management server managingthe autonomous driving service. The control device 100 acquires thedelivery information 54 by using the communication device 140 tocommunicate with the outside of the vehicle 1.

The driver input information 55 is information input by the driverthrough the HMI unit 150. The driver input information 55 indicates thesetting by the driver and the will of the driver.

The driver monitor information 56 is information acquired by the drivermonitor 160. For example, the driver monitor information 56 indicatesthe orientation of the face, the direction of eyes, and the eyeopening/closing degree of the driver.

It can be said that the control device 100, the GPS receiver 110, themap database 120, the sensor group 130, the communication device 140,the HMI unit 150, and the driver monitor 160 constitute the “informationacquisition device 20” shown in FIG. 2.

2-3. Autonomous Driving Control Device

The control device 100 controls the autonomous driving of the vehicle 1based on the driving environment information 50. In particular, thecontrol device 100 performs vehicle travel control that controls travelof the vehicle 1 based on the driving environment information 50. Morespecifically, the control device 100 creates a travel plan based on thedriving environment information 50. Then, the control device 100controls the travel device 180 to make the vehicle 1 travel inaccordance with the travel plan. It can be said that the control device100 and the travel device 180 constitute the “autonomous driving controldevice 30” shown in FIG. 2.

2-4. Interest Level Calculation Device

Furthermore, the control device 100 calculates the interest level IL ofthe driver. For example, the control device 100 can calculate theinterest level IL based on the driver monitor information 56. Forexample, the interest level IL is calculated to be lower as an anglebetween the orientation of the face of the driver and a front directionbecomes larger. A speech state is detected based on movement of thedriver's mouth, and the interest level IL is calculated to be low whenthe driver speaks.

As another example, the control device 100 can calculate the interestlevel IL based on the driver input information 55. For example, thespeech state is detected based on a microphone input of the HMI unit150, and the interest level IL is calculated to be low when the driverspeaks. Alternatively, the driver may use the input device of the HMIunit 150 to communicate the interest level IL to the autonomous drivingsystem 10.

As still another example, when the driver activates the media device 170to view contents, the interest level IL is considered to be low.Therefore, the control device 100 can calculate the interest level ILbased on whether or not the media device 170 is playing contents. Whenthe media device 170 is playing contents, the interest level IL iscalculated to be low.

As still another example, when the driver reclines the driver's seat,the interest level IL is determined to be low.

It can be said that the control device 100, the HMI unit 150, the drivermonitor 160, and the media device 170 constitute the “interest levelcalculation device 40” shown in FIG. 2.

2-5. Process Flow

FIG. 5 is a flow chart showing processing by the control device 100 ofthe autonomous driving system 10 according to the present embodiment.The flow shown in FIG. 5 is repeatedly executed every certain cycle.

In Step S10, the control device 100 (the interest level calculationdevice 40) calculates the interest level IL of the driver. In thesubsequent Step S20, the control device 100 compares the interest levelIL with a threshold. When the interest level IL is equal to or higherthan the threshold (Step S20; No=normal state), the processing proceedsto Step S30. On the other hand, when the interest level IL is lower thanthe threshold (Step S20; Yes=low interest state), the processingproceeds to Step S40.

In Step S30, the control device 100 (the autonomous driving controldevice 30) performs the autonomous driving control in thedriver-oriented mode. In the driver-oriented mode, the control device100 performs the autonomous driving control with giving priority to atleast one of the setting by the driver, the will (selection,instruction) of the driver, and the ride quality. For example, thedriver can use the input device of the HMI unit 150 to communicatepreferred settings (e.g. inter-vehicle distance, vehicle speed) and thedriver's will (e.g. approval or refusal of lane change proposal) to theautonomous driving system 10. The control device 100 recognizes thedriver's settings and will based on the driver input information 55 andgives priority to them. When giving priority to the ride quality, thecontrol device 100 performs the vehicle travel control with suppressingacceleration/deceleration.

In Step S40, the control device 100 (the autonomous driving controldevice 30) performs the autonomous driving control in theperformance-oriented mode. In the performance-oriented mode, the controldevice 100 performs the autonomous driving control with giving priorityto at least one of the standpoints (A) to (E) shown in FIG. 1. FIG. 6shows a variety of concrete examples of the autonomous driving controlin the performance-oriented mode. Hereinafter, concrete examples foreach of the standpoints (A) to (E) will be described.

3. Increase in Safety Margin

The standpoint (A) is increase in a safety margin. The autonomousdriving control device 30 performs the autonomous driving control withgiving priority to increase in the safety margin, regardless of thesetting by the driver or the will of the driver.

3-1. Lane Selection

A method of increasing the safety margin includes selecting a safe laneas a travel lane regardless of the setting by the driver or the will ofthe driver. In order to explain lane selection, let us first explain anexample of lane planning.

FIG. 7 is a flow chart showing an example of lane planning. In thepresent example, each lane is given a “score”. The score is used as acriterion for determining a travel lane in which the vehicle 1 actuallytravels. A lane having a higher score has more advantages.

First, in Step S100, the autonomous driving control device 30 gives ascore to each lane in consideration of a default lane (see FIG. 8). Thedefault lane is a lane in which the vehicle 1 basically travels.Typically, the default lane is a current lane in which the vehicle 1 iscurrently traveling. In an example shown in FIG. 8, a lane L2 is thedefault lane. The scores are first given such that the score of thedefault lane is the highest and the score becomes lower as away from thedefault lane.

In the subsequent Step S110, the autonomous driving control device 30performs score correction according to a target behavior. Then, theautonomous driving control device 30 performs the lane planning so thata sum of scores up to arrive at the destination becomes maximum (StepS120). Typically, a lane having the highest score is selected as thetravel lane in which the vehicle 1 travels. Then, the autonomous drivingcontrol device 30 performs the vehicle travel control such that thevehicle 1 travels in accordance with a result of the lane planning.

An example of the target behavior is a lane change. A situationrequiring the lane change is exemplified by lane merging, lanebranching, overtaking a low-speed preceding vehicle, and so forth. Thelane merging and the lane branching are recognized based on the mapinformation 52. The low-speed preceding vehicle is recognized by thesensor-detected information 53 (specifically, the target information).When the lane change is required, the autonomous driving control device30 performs the score correction such that the score of a target lane ofthe lane change becomes higher. As a result, the lane change becomeslikely to be performed.

(A1) Keep Left Driving

An example of the increase in the safety margin is to perform keep leftdriving. Information on the lane geometries is included in the mapinformation 52. As shown in FIG. 9, the autonomous driving controldevice 30 increases the score of a leftmost lane L1. Since the score ofthe lane L1 becomes the highest, the keep left driving is performed.

(A2) Select Lane not Adjacent to Wall

Another example of the increase in the safety margin is to select a lanethat is not adjacent to a wall. Information on the lane geometries isincluded in the map information 52. The autonomous driving controldevice 30 increases the score of the lane L2 that is not adjacent to anywall.

(A3) Select Lane with Less Adjacent Vehicle

A still another example of the increase in the safety margin is toselect a lane with less adjacent vehicle. In an example shown in FIG.10, the vehicle 1 is traveling in a lane L2 and there are a lot ofadjacent vehicles 2 in a lane L1 adjacent to the lane L2. The adjacentvehicle 2 can be recognized based on the sensor-detected information 53(specifically, the target information). The autonomous driving controldevice 30 decreases the score of the lane L2 to urge a lane change to alane L3 with less adjacent vehicles 2.

(A4) Avoid Merged Section

A still another example of the increase in the safety margin is to makethe vehicle 1 travel so as to avoid a merged section. In an exampleshown in FIG. 11, there is a merged section MS in a lane L1 ahead of thevehicle 1. That is, a merge lane LM merges with the merged section MS ofthe lane L1. The merged section MS can be recognized based on the mapinformation 52. The autonomous driving control device 30 decreases thescore of the merged section MS to urge to avoid the merged section MS.

3-2. Travel Control

The autonomous driving control device 30 performs the autonomous drivingcontrol with a margin distance to a surrounding vehicle. In FIG. 12, amargin distance between the vehicle 1 and a preceding vehicle 3 isdenoted by “D3”, and a margin distance (lateral margin) between thevehicle 1 and an adjacent vehicle 4 is denoted by “D4”. When aninter-vehicle distance between the vehicle 1 and the preceding vehicle 3becomes less than the margin distance D3, the autonomous driving controldevice 30 performs deceleration control to increase the inter-vehicledistance. When a lateral distance between the vehicle 1 and the adjacentvehicle 4 becomes less than the margin distance D4, the autonomousdriving control device 30 performs steering control to increase thelateral distance.

(A5) Enlarge Margin Distance to Preceding Vehicle

As still another example of the increase in the safety margin is toenlarge the margin distance D3 to the preceding vehicle 3. That is tosay, the autonomous driving control device 30 ignores the setting by thedriver and increases the margin distance D3 in the case of theperformance-oriented mode as compared with the case of thedriver-oriented mode.

(A6) Enlarge Margin Distance to Adjacent Vehicle

As still another example of the increase in the safety margin is toenlarge the margin distance D4 to the adjacent vehicle 4. That is tosay, the autonomous driving control device 30 ignores the setting by thedriver and increases the margin distance D4 in the case of theperformance-oriented mode as compared with the case of thedriver-oriented mode.

(A7) Advance Deceleration Timing

As still another example of the increase in the safety margin is toadvance a deceleration timing to start deceleration of the vehicle 1.For example, the autonomous driving control device 30 performsdeceleration of the vehicle 1 in front of a curve. The decelerationtiming to start deceleration is determined based on a current vehiclespeed, a target speed after deceleration, and a target deceleration. Forexample, it is possible to advance the deceleration timing by settingthe target deceleration to be lower. By advancing the decelerationtiming in the case of the performance-oriented mode as compared with thecase of the driver-oriented mode, the safety margin is increased.

3-3. Lane Change

(A8) Tighten Lane Changeable Condition

FIG. 13 is a conceptual diagram for explaining a lane changeablecondition. The vehicle 1 is traveling in a lane L2. A target lane of alane change is a lane L3 adjacent to the lane L2. A preceding vehicle 5is one closest to the vehicle 1 among preceding vehicles traveling inthe lane L3. A following vehicle 6 is one closest to the vehicle 1 amongfollowing vehicles traveling in the lane L3. The preceding vehicle 5 andthe following vehicle 6 can be recognized based on the sensor-detectedinformation 53 (specifically, the target information).

The lane changeable condition includes the following three conditions(a) to (c). That is, when all the following three conditions (a) to (c)are satisfied, the autonomous driving control device 30 judges that thelane change to the lane L3 is possible.

(a) An inter-vehicle distance D56 between the preceding vehicle 5 andthe following vehicle 6 is equal to or more than a first LC threshold.

(b) An inter-vehicle distance D5 between the vehicle 1 and the precedingvehicle 5 is equal to or more than a second LC threshold (the second LCthreshold may be expressed as a function of a relative speed between thevehicle 1 and the preceding vehicle 5).

(c) An inter-vehicle distance D6 between the vehicle 1 and the followingvehicle 6 is equal to or more than a third LC threshold (the third LCthreshold may be expressed as a function of a relative speed between thevehicle 1 and the following vehicle 6).

As still another example of the increase in the safety margin is totighten the lane changeable condition. In other words, the autonomousdriving control device 30 makes the lane changeable condition in thecase of the performance-oriented mode be harder to satisfy as comparedwith the case of the driver-oriented mode. It is possible to tighten thelane changeable condition by increasing at least one of the first tothird LC thresholds described above.

(A9) Increase Inter-Vehicle Distance at Start of Overtaking

FIG. 14 is a conceptual diagram for explaining an overtaking executioncondition. A preceding vehicle 7 slower than the vehicle 1 exists aheadof the vehicle 1. The preceding vehicle 7 can be recognized based on thesensor-detected information 53 (specifically, the target information).

The overtaking execution condition includes the following two conditions(d) and (e). That is, when all the following two conditions (d) and (e)are satisfied, the autonomous driving control device 30 startsovertaking processing for overtaking the preceding vehicle 7.

(d) An inter-vehicle distance D7 between the vehicle 1 and the precedingvehicle 7 is less than a first threshold.

(e) A relative speed “V1-V7” between the vehicle 1 and the precedingvehicle 7 is equal to or more than a second threshold.

As still another example of the increase in the safety margin is toincrease the inter-vehicle distance D7 at start of the overtaking. It ispossible to increase the inter-vehicle distance D7 at start of theovertaking by increasing the above-mentioned first threshold. That is,the autonomous driving control device 30 increases the first thresholdin the case of the performance-oriented mode as compared with the caseof the driver-oriented mode.

4. Reduction in Time to Arrive at Destination

The standpoint (B) is reduction in a time to arrive at the destination.The autonomous driving control device 30 performs the autonomous drivingcontrol with giving priority to reduction in the time to arrive at thedestination, regardless of the setting by the driver or the will of thedriver.

(B1) Actively Perform Overtaking

For example, it is possible to reduce the time to arrive at thedestination by actively performing overtaking. To this end, theautonomous driving control device 30 loosens the above-describedovertaking execution condition by decreasing the second threshold in theovertaking execution condition. In other words, the autonomous drivingcontrol device 30 decreases the second threshold in the case of theperformance-oriented mode as compared with the case of thedriver-oriented mode.

(B2) Stay in Fast Lane

As still another example, it is possible to reduce the time to arrive atthe destination by staying in a fast lane. In FIG. 15, the vehicle 1 istraveling in a lane L2. A preceding vehicle 8 exists in the lane L2ahead. Moreover, other vehicles 9 exist in lanes L1 and L3 adjacent tothe lane L2. The preceding vehicle 8 and the other vehicles 9 can berecognized based on the sensor-detected information 53 (specifically,the target information). When a speed of the preceding vehicle 8 ishigher than an average speed of the other vehicles 9 by a certain valueor more, the autonomous driving control device 30 judges that “a trafficflow in the lane L2 is faster than the other lanes L1 and L3”. In thiscase, the autonomous driving control device 30 increases the score ofthe lane L2 such that the vehicle 1 stays in the lane L2.

5. Improvement in Fuel Economy

The standpoint (C) is improvement in fuel economy. For example, it ispossible to improve the fuel economy by utilizing an eco-drive mode. Inthe case of the performance-oriented mode, the autonomous drivingcontrol device 30 may perform the vehicle travel control in theeco-drive mode, regardless of the setting by the driver or the will ofthe driver.

6. Improvement in Motion Performance

The standpoint (D) is improvement in motion performance. The autonomousdriving control device 30 performs the autonomous driving control withgiving priority to improvement in the motion performance rather than theride quality.

(D1) Increase Upper Limit of Acceleration/Deceleration

For example, the autonomous driving control device 30 increases upperlimits of acceleration and deceleration in the case of theperformance-oriented mode as compared with the case of thedriver-oriented mode. Here, the acceleration and deceleration includesnot only acceleration and deceleration in a longitudinal direction butalso a lateral acceleration (lateral G). Allowing the acceleration anddeceleration to be higher than the case of the driver-oriented modeimproves the motion performance of the vehicle 1.

(D2) Improve Following Performance

The autonomous driving control device 30 controls travel of the vehicle1 so as to follow a target trajectory. Increase in a control gain of thevehicle travel control can increase the following performance, althougha feeling of vibration increases and thus the ride quality deterioratesat the same time. That is to say, there is a trade-off relationshipbetween the following performance and the ride quality. The autonomousdriving control device 30 increases the control gain in the case of theperformance-oriented mode as compared with the case of thedriver-oriented mode.

(D3) Shorten Time to Wait for Driver to Complete Situation Check

In a case where the autonomous driving control device 30 makes a lanechange, the driver also may desire to check a situation around thevehicle 1. However, the autonomous driving control device 30 and thedriver (human) are different in information processing ability, and theautonomous driving control device 30 is able to process more informationmore quickly as compared with the driver. Therefore, even when theautonomous driving control device 30 judges that a lane change ispossible, it is highly probable that the driver does not yet completejudgment.

In view of the above, in the case of the driver-oriented mode, theautonomous driving control device 30 delays a start timing of the lanechange for a certain period of time in order to wait for the driver tocomplete the situation check. In other words, the autonomous drivingcontrol device 30 waits for a while after judging that the lanechangeable condition (see FIG. 13) is satisfied and then starts the lanechange.

On the other hand, in the case of the performance-oriented mode, theautonomous driving control device 30 gives priority to improvement inthe motion performance rather than consideration for the driver.Therefore, the autonomous driving control device 30 advances the starttiming of the lane change as compared with the case of thedriver-oriented mode. As a result, the lane change is performed quickly.

7. Reduction in Frequency of Notification

The standpoint (E) is reduction in a frequency of notification to thedriver. The autonomous driving control device 30 notifies the driver ofa variety of information through the output device of the HMI unit 150.The higher the frequency of notification becomes, the will of the driverbecomes more likely to be reflected in the autonomous driving control.Conversely, the lower the frequency of notification becomes, the will ofthe driver becomes less likely to be reflected in the autonomous drivingcontrol.

(E1) Refrain from Asking Driver for Will

The autonomous driving control device 30 can ask the will of the driverthrough the HMI unit 150. For example, the autonomous driving controldevice 30 proposes a predetermined vehicle behavior to the driver. Thevehicle behavior to be proposed is exemplified by a lane change,overtaking, keep left driving, and so forth. The driver uses the HMIunit 150 to approve or refuse the proposed vehicle behavior. As anotherexample, the autonomous driving control device 30 presents a pluralityof candidates as a travel route to the destination. The driver uses theHMI unit 150 to select a desired travel route from the plurality ofcandidates.

In the case of the driver-oriented mode, the autonomous driving controldevice 30 asks the will of the driver. It is thus possible to recognizethe will of the driver and reflects the will of the driver in theautonomous driving control. On the other hand, in the case of theperformance-oriented mode, the autonomous driving control device 30performs the autonomous driving control on it's own judgment withoutasking the will of the driver.

(E2) Reduce Number of Times of Lane Change

As another example, in the lane planning (see FIG. 7), the autonomousdriving control device 30 may reduce the number of times of lane change.For example, a “negative score” is added to the sum of scores each timea lane change is incorporated into the travel plan. As a result, thenumber of times of lane change is suppressed. Since the number of timesof lane change is reduced, the autonomous driving control device 30 lessfrequently makes a proposal of a lane change to the driver. As a result,the will of the driver becomes less likely to be reflected in theautonomous driving control.

What is claimed is:
 1. An autonomous driving system mounted on a vehiclecomprising: a processor programmed to: control autonomous driving of thevehicle, wherein modes of the autonomous driving include: (i) adriver-oriented mode in which the autonomous driving control devicegives priority to at least one of setting by the driver, will of thedriver, and ride quality; and (ii) a performance-oriented mode in whichthe autonomous driving control device gives priority to at least one ofincrease in a safety margin, reduction in a time to arrive at adestination, improvement in fuel economy, improvement in motionperformance, and reduction in a frequency of notification to the driver;calculate an interest level of a driver of the vehicle for theautonomous driving, wherein a low interest state is a state where theinterest level is lower than a normal state; and control the autonomousdriving in the driver-oriented mode when the interest level iscalculated to be the normal state; and control the autonomous driving inthe performance-oriented mode when the interest level is calculated tobe the low interest state.
 2. The autonomous driving system according toclaim 1, wherein when increasing the safety margin in theperformance-oriented mode, the processor is further programmed toperform keep left driving regardless of the setting by the driver or thewill of the driver.
 3. The autonomous driving system according to claim1, wherein when a merge lane merges with a merged section of a firstlane ahead of the vehicle, and when increasing the safety margin in theperformance-oriented mode, the processor is further programmed to makethe vehicle travel so as to avoid the merged section regardless of thesetting by the driver or the will of the driver.
 4. The autonomousdriving system according to claim 1, wherein the processor is furtherprogrammed to: perform the autonomous driving with a margin distance toa surrounding vehicle, and when increasing the safety margin in theperformance-oriented mode, increase the margin distance as compared witha case of the driver-oriented mode.
 5. The autonomous driving systemaccording to claim 1, wherein the processor is further programmed to:when a lane changeable condition is satisfied, judge that a lane changeis possible, and when increasing the safety margin in theperformance-oriented mode, make the lane changeable condition be harderto satisfy as compared with a case of the driver-oriented mode.
 6. Theautonomous driving system according to claim 1, wherein the processor isfurther programmed to: when an overtaking execution condition issatisfied, start overtaking processing for overtaking a precedingvehicle, the overtaking execution condition includes that aninter-vehicle distance between the vehicle and the preceding vehicle isless than a first threshold, and when increasing the safety margin inthe performance-oriented mode, increase the first threshold as comparedwith a case of the driver-oriented mode.
 7. The autonomous drivingsystem according to claim 1, wherein the processor is further programmedto: when an overtaking execution condition is satisfied, startovertaking processing for overtaking a preceding vehicle, the overtakingexecution condition includes that a relative speed between the vehicleand the preceding vehicle is equal to or more than a second threshold,and when reducing the time to arrive at the destination in theperformance-oriented mode, decrease the second threshold as comparedwith a case of the driver-oriented mode.
 8. The autonomous drivingsystem according to claim 1, wherein when improving the motionperformance in the performance-oriented mode, the processor is furtherprogrammed to increase upper limits of acceleration and deceleration ofthe vehicle as compared with a case of the driver-oriented mode.
 9. Theautonomous driving system according to claim 1, wherein when improvingthe motion performance in the performance-oriented mode, the processoris further programmed to a advance a start timing of a lane change ascompared with a case of the driver-oriented mode.
 10. The autonomousdriving system according to claim 1, wherein when reducing the frequencyof notification in the performance-oriented mode, the processor isfurther programmed to perform the autonomous driving without asking thewill of the driver.